The wavelength division multiplexing (WDM) optical transmission system transmitting signals by multiplexing different wavelengths on a single optical fiber has been put into practical use as long haul and large capacity communication medium.
FIG. 1 shows a diagram illustrating an overall configuration example of the wavelength division multiplexing optical transmission system. A transmission unit 10 is constituted of a plurality of optical transmitters 12-1, 12-2, . . . 12-n. From each optical transmitter, light of different wavelengths is transmitted and input into a multiplexer unit 22 in a WDM unit 20 on the transmission side. Multiplexer unit 22 has a plurality of ports which receives a plurality of different wavelengths (λ1, λ2, . . . λn). Optical signals input to each port are multiplexed in multiplexer unit 22. The multiplexed optical signals are then amplified by an optical amplifier 24 in WDM unit 20, and forwarded to a transmission line 30. The optical signals are amplified in optical relay units 32 disposed in the middle of transmission line 30, and reach a demultiplexer 42 of a WDM unit 40 on the receiving side. In demultiplexer 42, the optical signals are demultiplexed to each optical signal of different wavelength.
To introduce the wavelength division multiplexing optical transmission system, complicated wiring and a multiplicity of optical transmitters are necessary. Therefore, a vast amount of time and work are necessary for such setting and wiring at the time of installation and expansion.
Here, an exemplary installation procedure of a new channel according to the conventional method is described in the following.
(1) Inserting an optical transmitter into a vacant slot of a shelf for mounting a plurality of optical transmitters in the transmission unit.
(2) Connecting and setting a WDM unit (such as optical multiplexer and optical amplifier), and initiating the WDM unit.
(3) Connecting the optical transmitter to a designated port of the multiplexer in the WDM unit, while verifying using a wiring diagram, etc.
(4) Setting an optical transmitter wavelength to the wavelength of the connected port.
In particular, in the above work (4), when connecting a multiplicity of optical transmitters to the respective ports in the multiplexer of the WDM unit, it is necessary to set the transmission wavelength of each transmitter to the wavelength corresponding to the connected port. Conventionally, a worker sets this work manually by referring to the diagram.
However, this manual work of setting each transmission wavelength to the transmitter is time-consuming and may possibly induce incorrect setting. Once such an incorrect setting occurs, various problems may occur, such as delayed start of normal operation and extra operation cost.
As such, when installing or expanding the wavelength division multiplexing optical transmission system, and when setting a multiplicity of channels is required, it is necessary to install, or expand, a multiplicity of optical transmitters corresponding to the number of channels. This requires an increased load of workers on site, and therefore reduction of the work has been desired.